Isolator and suspension assembly for riding equipment

ABSTRACT

A biasing element provides suspension between a pivoting component and a support area of a riding outdoor power equipment vehicle, and can include a body compressible between a default unbiased orientation and a compressed orientation. The body can include annular portions having a radially outer main portion circumscribing radially inner portions. The radially inner portions being vertically spaced apart when the body is in the default orientation and movable into engagement with one another upon compression of the body.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 16/571,756 filed Sep. 16, 2019, which is incorporated herein byreference in its entirety.

FIELD OF INVENTION

Aspects of the disclosed technology relate generally to riding equipmentand more particularly to a suspension assembly for resisting movement ofan operator platform of outdoor riding equipment, such as equipmentincluding a mower deck for cutting vegetation, such as a riding mower.

BACKGROUND

Riding equipment, whether for indoor use, outdoor use, or a combinationof indoor and outdoor use, can include a sitting platform or a standingplatform operating in conjunction with a suspension assembly forsupporting an operator or rider. The suspension assembly is provided tocushion the rider by damping forces seen by the riding equipment,lessening the transfer of these forces to the operator. Typicalsuspension assemblies control or restrict movement between an operatorplatform (sitting, standing, or a combination thereof) and a chassis ofthe riding equipment. These typical suspension assemblies often are“one-size-fits-all” assemblies that do not account for varying weightsof varying operators. In such cases, the biasing spring rate resistingmovement of the operator platform is the same for both a lower weightoperator and a heavier weight operator, making the riding experienceuncomfortable for at least one of these rider classes.

SUMMARY OF INVENTION

Aspects of the disclosed technology may address one or more of theseissues and may additionally or alternatively address other issues insuspension assemblies of riding equipment.

Disclosed is a riding power equipment vehicle, such as a riding outdoorpower equipment vehicle for grounds maintenance, having a chassisincluding a support area, an operator platform for supporting a riderand supported by the chassis, and a suspension assembly. The suspensionassembly is configured to resist movement of the operator platformtowards the support area of the chassis and includes a biasing elementconfigured to provide suitable deflection with lower weights applied tothe operator platform and to reduce the deflection upon greater weightbeing applied to the operator platform while maintaining adequateisolation of an operator from forces seen by the riding equipmentvehicle during use.

The suspension may include one or more biasing elements, each having aplurality of annular portions. At least two annular portions of theplurality of annular portions are spaced apart from one another when thebiasing element is in a default orientation and are moved intoengagement with one another upon compression of the biasing elementbetween the operator platform and the support area. Compression of thebiasing element provides an initial deflection response whose ratedecreases substantially in response to increasing loading being appliedto the operator platform.

According to one aspect, a riding outdoor power equipment vehicleincludes a chassis supporting one or more ground engaging members forallowing movement of the vehicle. The chassis includes a support area,an operator platform supported by the chassis for pivoting movementrelative to the support area between an operating position and adisengaged position, and a suspension assembly disposed between theoperator platform and the support area when the operator platform is inthe operating position. The suspension assembly is configured to becompressed to resist movement of the operator platform towards thesupport area. The support area supports the operator platform when thesuspension assembly is engaged between the operator platform and thesupport area. The suspension assembly includes at least one biasingelement having a body defining at least three annular portions. The atleast three annular portions include a radially outer main portioncircumscribing a pair of radially inner portions. The pair of radiallyinner portions are vertically spaced apart from one another when the atleast one biasing element is in a default orientation and are movableinto engagement with one another upon compression of the biasing elementbetween the operator platform and the support area.

The pair of radially inner portions each may extend along a respectiveportion axis, which portion axes are aligned parallel to one another.

The portion axes may extend transverse a pivot axis of the operatorplatform.

The at least three annular portions each may extend along respectiveportion axes that are each aligned parallel to one another.

The body of the biasing element may extend between opposing first andsecond faces, and each of the annular portions may have a constantprofile extending between the first face and the second face.

The pair of radially inner portions each may share a common annulussector with the radially outer main portion.

The pair of radially inner portions may include a vertically upperannular portion and a vertically lower annular portion, and thevertically lower annular portion may be configured to have a faster rateof compression than the vertically upper annular portion.

The pair of radially inner portions may include a vertically upperannular portion and a vertically lower annular portion, and the biasingelement may be configured such that compression of the radially outermain portion provides a greater compression distance per unit of forceapplied to the biasing element than is provided by subsequentcompression of the vertically lower annular portion.

The compressible element may be configured such that engagement of thebiasing element between the operator platform and the support areacauses compression of the radially outer main portion prior tocompression of either of the pair of radially inner portions.

The biasing element may include a retention member extending from theradially outer main annular portion for engaging in a slot of thesupport area or of the operator platform to fix position of the biasingelement relative to a pivot axis of the operator platform.

The biasing element may comprise a single molded article having unitaryconstruction.

The biasing element may be configured to resist inelastic compression.

The suspension assembly further may include a pair of biasing elementsspaced apart from one another and fixed relative to a pivot axis of theoperator platform.

According to another aspect, a riding outdoor power equipment vehicleincludes a chassis supporting one or more ground engaging members forallowing movement of the vehicle, and the chassis includes a supportarea. An operator platform is supported by the chassis for pivotingmovement relative to the support area between an operating position anda disengaged position. A suspension assembly is disposed between theoperator platform and the support area when the operator platform is inthe operating position. The suspension assembly is configured to becompressed to resist movement of the operator platform towards thesupport area. The support area supports the operator platform when thesuspension assembly is engaged between the operator platform and thesupport area. The suspension assembly includes at least one biasingelement having a pair of annular portions each defining a respectivecavity extending at least partially therethrough. The annular portionsare connected to one another via radially outwardly spaced resilientportions forming with the pair of annular portions a radially outerannular portion circumscribing the respective cavities of the pair ofannular portions.

The pair of annular portions may be spaced from one another by theradially outwardly spaced resilient portions when the biasing element isin a default unbiased orientation.

The compressible element may have a body defining at least threecavities extending therethrough along respective parallelly-alignedcavity axes.

According to yet another aspect, a biasing element for providingsuspension between a pivoting component and a support area of a ridingoutdoor power equipment vehicle includes a body compressible between adefault unbiased orientation and a compressed orientation. The body hasat least three annular portions. The at least three annular portionsinclude a radially outer main portion circumscribing a pair of radiallyinner portions. The pair of radially inner portions are verticallyspaced apart from one another when the body is in the defaultorientation and are movable into engagement with one another uponcompression of the body. At least one retaining member is provided forallowing fixing of the body.

The biasing element may comprise a single molded article having unitaryconstruction.

The pair of radially inner portions may include a vertically upperannular portion and a vertically lower annular portion, and thevertically lower annular portion may be configured to have a faster rateof compression than the vertically upper annular portion.

The pair of radially inner portions may include a vertically upperannular portion and a vertically lower annular portion, and the body maybe configured such that compression of the radially outer main portionprovides a greater compression distance per unit of force applied to thebody than is provided by subsequent compression of the vertically lowerannular portion.

The foregoing and other features of the disclosed technology arehereinafter described in greater detail with reference to theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The annexed drawings, which are not necessarily to scale, show variousaspects of the disclosure.

FIG. 1 is an environmental view of a riding mower including an operatorplatform and associated suspension assembly according to the presentdisclosure.

FIG. 2 is a partial view of the riding vehicle of FIG. 1 , with portionsof the body removed to allow for visibility of the chassis.

FIG. 3 is a partial rear view of the riding mower of FIG. 1 .

FIG. 4 is yet another partial rear view of the riding mower of FIG. 1 .

FIG. 5 is an orthogonal view of a biasing element of the suspensionassembly of the riding mower of FIG. 1 depicted apart from the ridingvehicle.

FIG. 6 is a front view of the biasing element of FIG. 5 .

FIG. 7 is a side view of the biasing element of FIG. 5 .

FIG. 8 is a bottom view of the biasing element of FIG. 5 .

FIG. 9 is a cross-sectional view of the biasing element of FIG. 5 ,taken along the line Y-Y of FIG. 6 .

FIG. 10 is an exemplary spring compression vs. force graph detailingcompression of the biasing element depicted at FIG. 5 .

DETAILED DESCRIPTION

The principles of the present disclosure have general application toriding equipment, whether for sitting, standing or a combination ofboth, and whether indoor or outdoor riding equipment. More particularapplication is to outdoor riding equipment such as a sitting mower.Thus, while the present disclosure is majoratively direct to a sittingmower, the suspension assembly disclosed also has utility for inclusionwith non-mowing, standing or non-outdoor riding equipment, among othercategories.

A riding outdoor power equipment vehicle of the present disclosureincudes a chassis, an operator platform, and a suspension assembly. Thesuspension assembly is configured to restrict movement of the operatorplatform relative to the chassis, and in particular, towards a supportarea of the chassis. Generally, the suspension assembly is notposition-adjustable and is fixed relative to the chassis. Although, inother embodiments, the suspension assembly may be selectively moveablerelative to the chassis.

The suspension assembly includes one or more biasing elements that areconfigured to be disposed between the operator platform and the supportarea of the chassis to resist movement of the operator platform towardsthe support area. The biasing element is constructed to function withvarying loadings applied to the operator platform. With the varyingloadings, reduced deflection rate of the operator platform is enabled athigher loadings via the unique construction of the biasing element,allowing for a more uniform riding experience for operators of variedweights.

Turning now to FIG. 1 , a riding outdoor power equipment vehicle 10,such as a riding mower is depicted including an operator platform 12 forsupporting an operator of the vehicle 10. The operator platform 12 issupported by a chassis 14 that also supports an external body 18 of thevehicle 10. A drive system 24 is further supported by the chassis 14 formoving the vehicle 10 about a work area. The drive system 24 includesone or more surface engaging movable members 26.

The movable member 26 are shown as two pairs of wheels, including a pairof front wheels 28 longitudinally spaced from a pair of rear wheels 30along a central longitudinal axis 32 of the vehicle 10. In otherembodiments, other members may be utilized, such as treads, skis, etc.and fewer than four total members may be included.

The vehicle 10 includes a ground maintenance element 34, which in thedepicted vehicle is illustrated as a mowing deck. In other embodiments,the deck may be omitted or an alternative element 34 may be include.

The operator platform 12 is disposed at a rear 36 of the vehicle 10,along the central longitudinal axis 32. A seat 38 is coupled to theoperator platform 12 for allowing comfortable riding by the operator.Turning to FIGS. 2 to 4 , the operator platform 12 is supported by thechassis 14 for pivoting movement relative to the chassis. In particular,the operator platform 12 is coupled to the chassis 14 via pivotingmembers (not specifically shown) such as hinges. Pivoting of theoperator platform 12 is conducted about a platform pivot axis 40, whichaxis is fixed relative to the chassis 14. The operator platform 12 isallowed to pivot between an operating position for supporting theoperator, shown in FIG. 3 , and a disengaged position, spaced, such asupwardly spaced, from the operating position, as shown in FIG. 4 .

As shown in FIGS. 2 to 4 , the chassis 14 includes a support area 42.The support area 42 is depicted as a portion of an elevated crossmember44 of the chassis 14, but the support area 42 may be otherwise shapedrelative to a remainder of the chassis 14 in other embodiments. Thesupport area 42 is disposed such that it is situated co-longitudinallyalong the longitudinal axis 32 with at least a portion of the operatorplatform 12, and as depicted, with a rear portion of the operatorplatform 12.

The vehicle 10 further includes a suspension assembly 60 for supportingthe operator platform 12 and the weight of an operator loaded at theoperator platform 12. The suspension assembly 60 is generally disposedbetween the operator platform 12 and the support area 42 when theoperator platform 12 is in the operating position. The depictedembodiment includes the suspension assembly 60 coupled to the chassis 14at the support area 42. In this way, the support area 42 supports theoperator platform 12 when the suspension assembly 60 is engaged betweenthe operator platform 12 and the support area 42. In other embodiments,the suspension assembly 60 instead may be coupled to the operatorplatform 12, such as to an underside 62 of the operator platform 12.

The suspension assembly 60 is configured to be compressed to resistmovement of the operator platform 12 towards the support area 42 duringcompression of the suspension assembly 60, such as between the operatorplatform 12 and the support area 42. Generally, the suspension assemblyallows for isolation of the operator from at least a portion of forcesseen by the vehicle 10 during its use. For example, a vehicle traversinguneven ground can be imparted with jostling forces greater thanaccounted for by suspension elements coupled to the moveable members 26,or typical vibrations from the moving vehicle 10 can be transferredtowards the operator. To provide a reduction in jostling or vibrationfor the operator, the suspension assembly 60 can reduce impact to theoperator via a biasing spring force of the suspension assembly 60(including the possibility of dampening from the polymer incorporatedinto the suspension assembly 60).

The depicted suspension assembly 60 includes a pair of biasing elements70 laterally spaced apart from one another across the longitudinal axis32. The biasing elements 70 are coupled to the chassis 14, andparticularly to the support area 42 for fixing the location of thebiasing element 70 relative to the pivot axis 40. In some otherembodiments, any suitable number of biasing elements 70 may be included,such as being adequately spaced apart to prevent contact with oneanother during compression.

The operator platform 12 includes a contacting portion 72 that isconfigured, such as being shaped to engage the biasing elements 70coupled to the support area 42. The contacting portion 72 is arranged tosimultaneously contact each of the biasing elements 70.

A limiting portion 74 extends from the underside 62 of the operatorplatform 12, providing a hard stop for downward movement of the operatorplatform 12 towards the support area 42. The limiting portion 74 isarranged to contact a portion of the support area 42, such as laterallyintermediate between the biasing elements 70. Each of the limitingportion 74 and the contacting portion 72 may be alternative shapes inother embodiments.

Turning now to FIGS. 5 to 9 , a biasing element 70 is depicted apartfrom the support area 42. It will be appreciated that the biasingelements 70 depicted in FIGS. 2 to 4 are each identical, but may beotherwise constructed in alternative embodiments.

The biasing element 70 includes a body 78 that is generally configuredto resist inelastic compression, such that the biasing element 70provides for repeatable and repeated use. The depicted body 78 is asingle article, such as a molded article, having unitary construction.Accordingly, the biasing element 70 is formed as a single unit absentsecondary attachments or selectively removable portions. The body 78 maybe formed via any suitable molding process, such as injection molding,extrusion molding, etc.

Suitable materials from which the biasing element 70 can be made includepolymers that have minimal to no loss of deflection values at high orlow temperatures, allowing for continued biasing of the operatorplatform 12 when the riding vehicle 10 is used in both temperatureextremes. In one embodiment Arnitel, such as Arnitel PL581 may be used.In other embodiments a Keyflex BT material or thermoplastic copolyesterelastomer may be used.

The biasing element body 78 extends along a longitudinal extent betweenfront and rear faces 80 and 82. The body 78 is generally ovular in shapeand includes a generally flat bottom 84 for allowing stable engagementwith the support area 42. One or more retaining portions 86 extend fromthe bottom 84 to allow for coupling with the support area 42, and fixingof the biasing element 70 relative to the pivot axis 36 of the operatorplatform 12.

The body 78 has a lateral width in a range between about 3 inches andabout 6 inches, such as a range of about 4 inches to about 6 inches,such as about 5 inches. An overall height of the body 78 absent theretaining portions 86 may be in the range of about 2 inches to about 4inches, or about 2.5 inches to about 3.5 inches, or about 3 inches.Accordingly, the body 78 absent the retaining portions 86 has a greaterwidth than vertical height.

In the depicted embodiment, a pair of the retaining portions 86, alsoherein referred to as retention members, extend from the bottom 84 andare laterally spaced from one another along the bottom 84. Each of theretaining portions 86 includes a biasing sub-portion 90 that iscompressible to allow for insertion into a slot of the support area 42,but that returns to a default position after insertion to preventremoval of the biasing element 70 relative to the support area 42. Forexample, the crossmember 44 having the support area 42 may include aninner cavity (not shown) into which the biasing sub-portion 90 isinserted, where the biasing sub-portion 90 may expand from a compressedorientation (allowing the retaining portion 86 to enter the slot) to adefault orientation. In some embodiments, any suitable number of biasingsub-portions 90 may be included.

The body 78 defines at least a pair of annular portions 100 and 102 thatare vertically spaced part from one another along a central verticalaxis 104 of the biasing element 70 when the body 78 is in a defaultorientation. Each of the annular portions 100 and 102 extends completelybetween the front face 80 and the rear face 82 of the body 78, and eachdefines a respective cavity 106 and 108 also extending between the frontand rear faces 80 and 82. In the depicted embodiment, each of thecavities 106 and 108 has a constant shape extending along thelongitudinal extent 79. Likewise, each of the annular portions 100 and102 has a constant profile extending along the longitudinal extent 79.

In other embodiments, one or more of the cavities 106 and 108 may extendonly partially along the longitudinal extent 79. Additionally oralternatively, one or more of the cavities 106 and 108 may have anon-constant shape extending along the longitudinal extent 79, and/orone of the annular portions 100 and 102 may have a non-constant profileextending along the longitudinal extent 79.

The annular portions 100 and 102 are connected to one another via a pairof opposing radially outwardly spaced resilient portions 112. Theseportions 112 form with the pair of annular portions 100 and 102 aradially outer annular portion 114 that circumscribes each of thecavities 106 and 108 and the pair of annular portions 100 and 102. Thus,the annular portions 100 and 102 may be referred to as radially innerannular portions.

Turning specifically to FIG. 6 , each of the inner annular portions 100and 102 shares with the radially outer portion 114 a common annulussector. The inner annular portion 100 shares the vertically upper commonannulus sector 120 with the radially outer portion 114, and the innerannular portion 102 shares the vertically lower common annulus sector122 with the radially outer portion 114.

The body 78 forming each of the inner and outer annular portions 100,102 and 114 has sectors of similar thickness in the illustratedembodiment. In other embodiments, one or more annular portions may haveone or more sectors of different thickness.

A central cavity 118 is defined by the body 78 and extends centrallyalong the longitudinal extent. The central cavity 118 is formed in partby each of the inner and outer annular portions 100, 102 and 114.

Turning specifically to FIG. 9 , each of the three cavities 106, 108 and118 (and likewise the three annular portions 100, 102 and 114) extendalong respective parallelly-aligned cavity axes 130, 132 and 134. Theaxes 130, 132 and 134 are aligned transverse the pivot axis 36 of theoperator platform 12, such as being orthogonal to the pivot axis 36. Inother embodiments one or more of the axes 130, 132 and 134 may extendnon-parallelly to the other of the axes 130, 132 and 134.

During compression of the biasing element 70 from its default unbiasedorientation to an initial compressed orientation, engagement of thebiasing element 70 between the operator platform 12 and the support area42 causes compression of the radially outer main portion 114 prior tocompression of either of the pair of radially inner portions 100 and102. For lower weight operators, initial compression of the radiallyouter main portion 114 may not bring the pair of radially inner portions100 and 102 into engagement with one another. Accordingly, the biasingelement 70 is configured such that the annular portions compress insuccession.

Via construction of the body 78, compression of the radially outer mainportion 114 provides a greater compression distance per unit of forceapplied to the biasing element 70 than is provided by subsequentcompression of the vertically lower annular portion 102. Thus, theoperator platform 12 may have greater deflection rate towards thesupport area 42 for lower and intermediate loads (weighted operators).

Subsequent to initial compression of the radially outer main portion114, the inner portions 100 and 102 can be vertically brought intoengagement with one another. The vertically lower annular portion 102 isconfigured to have a faster rate of compression than the verticallyupper annular portion 100. And thus when brought into engagement withone another, the vertically upper annular portion 100 will engage andcause compression of the vertically lower portion 102, such as inrelation to a heavier loading at the operator platform. It will beappreciated that at this point the outer main portion 114 and the innerportions 100 and 102 are all compressing at different rates.

Turning now to FIG. 10 , a force vs. compression graph 140 of theloading of the biasing element 70 is provided, further detailing thesuccession of compression of the plurality of annular portions 100, 102and 114. It will be appreciated that this can also be thought of asloading versus compression. While FIG. 10 includes exemplary values, itwill be appreciated that aspects of the disclosed technology are notlimited to the exemplary values shown in FIG. 10 . The exemplary graph140 includes three interconnected sections 142, 144 and 146. The graphbegins at 0 deflection and 0 loading, referring to the defaultorientation of the biasing element 70. The first section 142 correspondswith compression of the radially outer annular portion 114. Inaccordance with on example, the first section 142 represents a gradualincrease in deflection caused by an operator load of about 0 lbs toabout 125 lbs. At about 125 lbs deflection (vertically downward) of thebiasing element 70 along the vertical axis 104 is about 0.55 inches.

At the second section 144, the vertically upper annular portion 100engaged the vertically lower annular portion 102. This engagementcompresses the vertically lower annular portion 102, while the radiallyouter annular portion continues to compress. At approximately 125 lbs ofloading, the vertically lower and upper annular portions 102 and 100engage. The second section 144 represents another gradual deflection,ending at approximately 450 lbs of loading and about 1.2 inches ofdeflection along the vertical axis 104. This represents the typicalmaximum loading via an operator.

At the max loading of the second section 144, a vertically upper sectorof the vertically lower annular portion 102 has been vertically loweredan intermediate amount. At the third section 146, the initial deflectionresponse has decreased substantially in response to increased loadingbeing applied to the operator platform 12. Continued deflection of thevertically upper annular portion 100 into the space previously occupiedby the lower cavity 108 continues until maximum deflection, wherein theupper sector engages the lower sector of the vertically lower annularportion 102.

In summary, a riding outdoor power equipment vehicle 10, such as forgrounds maintenance, has a chassis 14 including a support area 42, anoperator platform 12 for supporting a rider and supported by the chassis14, and a suspension assembly 60. The suspension assembly 60 isconfigured to resist movement of the operator platform 12 towards thesupport area 42 of the chassis 14 and includes a biasing element 70having a plurality of annular portions 100, 102 and 114. At least twoannular portions 100 and 102 of the plurality of annular portions 100,102 and 114 are spaced apart from one another when the biasing element70 is in a default orientation and are moved into engagement with oneanother upon compression of the biasing element 70 between the operatorplatform 12 and the support area 42. Compression of the biasing element70 provides an initial deflection response that decreases substantiallyin response to increasing loading being applied to the operator platform12.

Although the disclosed technology has been shown and described withrespect to a certain preferred aspect, embodiment or embodiments, it isobvious that equivalent alterations and modifications will occur toothers skilled in the art upon the reading and understanding of thisspecification and the annexed drawings. In particular regard to thevarious functions performed by the above described elements (components,assemblies, devices, members, compositions, etc.), the terms (includinga reference to a “means”) used to describe such elements are intended tocorrespond, unless otherwise indicated, to any element which performsthe specified function of the described element (i.e., that isfunctionally equivalent), even though not structurally equivalent to thedisclosed structure which performs the function in the hereinillustrated exemplary aspect, embodiment or embodiments of the disclosedtechnology. In addition, while a particular feature of the disclosedtechnology may have been described above with respect to only one ormore of several illustrated aspects or embodiments, such feature may becombined with one or more other features of the other embodiments, asmay be desired and advantageous for any given or particular application.

1. A biasing element for providing suspension between a pivotingcomponent and a support area of a riding outdoor power equipmentvehicle, the biasing element comprising: a body compressible between adefault unbiased orientation and a compressed orientation; the bodyhaving at least three annular portions, the at least three annularportions including a radially outer main portion circumscribing a pairof radially inner portions, the pair of radially inner portions beingvertically spaced apart from one another when the body is in the defaultorientation and movable into engagement with one another uponcompression of the body; and at least one retaining member for allowingfixing of the body.
 2. The biasing element of claim 1, wherein thebiasing element comprises a single molded article having unitaryconstruction.
 3. The biasing element of claim 1, wherein the pair ofradially inner portions include a vertically upper annular portion and avertically lower annular portion, and wherein the vertically lowerannular portion is configured to have a faster rate of compression thanthe vertically upper annular portion.
 4. The biasing element of claim 1,wherein the pair of radially inner portions include a vertically upperannular portion and a vertically lower annular portion, and wherein thebody is configured such that compression of the radially outer mainportion provides a greater compression distance per unit of forceapplied to the body than is provided by subsequent compression of thevertically lower annular portion.
 5. The biasing element of claim 1,wherein the pair of radially inner portions each extend along arespective portion axis, which portion axes are aligned parallel to oneanother.
 6. The biasing element of claim 5, wherein the portion axesextend transverse a pivot axis of the operator platform.
 7. The biasingelement of 1, wherein the at least three annular portions each extendalong respective portion axes that are each aligned parallel to oneanother.
 8. The biasing element of claim 1, wherein the body of thebiasing element extends between opposing first and second faces, andwherein each of the annular portions has a constant profile extendingbetween the first face and the second face.
 9. The biasing element ofclaim 1, wherein the pair of radially inner portions each share a commonannulus sector with the radially outer main portion.
 10. The biasingelement of claim 1, wherein the compressible element is configured suchthat engagement of the biasing element between the operator platform andthe support area causes compression of the radially outer main portionprior to compression of either of the pair of radially inner portions.11. The biasing element of claim 1 comprising, a retention memberextending from the radially outer main annular portion for engaging in aslot of the support area or of the operator platform to fix position ofthe biasing element relative to a pivot axis of the operator platform.12. The biasing element of claim 1, wherein the biasing element isconfigured to resist inelastic compression.
 13. The biasing element ofclaim 1, wherein the compressible element has a body defining at leastthree cavities extending therethrough along respectiveparallelly-aligned cavity axes.
 14. The biasing element of claim 1,wherein the biasing element comprises a single molded article havingunitary construction, and the biasing element is configured to resistinelastic compression.